1. Field of the Invention
This invention relates to high speed rod rolling mills, and is concerned in particular with an improvement to the laying heads employed in such mills to form the hot rolled product into a series of rings.
2. Description of the Prior Art
With reference to FIG. 1, a typical laying head includes a housing 10 containing a rotatably driven hollow quill 12. A three dimensionally curved laying pipe 14 is carried by the quill 12. The laying pipe has an entry end 14a aligned with the rotational axis X of the quill, and a curved intermediate section 14b leading to a delivery end 14c spaced radially from axis X.
Hot rolled steel rod is delivered to the entry end 14a of the delivery pipe along axis X, and exits from the delivery end 14c as a helical formation of rings.
Upon exiting from the delivery end 14c of the laying pipe, the rings are additionally confined and moved forward by a helical trough 16 surrounded by a cylindrical shroud 18.
The guide trough 16 is configured and dimensioned to coact with the shroud 18 in providing an axially and radially confined helical extension of the guide path defined by the laying pipe. Although this extended confinement has proven to be highly beneficial in resisting distortion and kinking of the tail ends of products passing through the laying head, the unitary construction of the guide trough has given rise to certain difficulties. For example, the materials that can be readily formed or machined into a helical configuration are relatively soft and thus prone to accelerated wear caused by frictional contact with the hot rolled product. Although accelerated frictional wear typically occurs only locally along short sections of the guide path, the entire trough must be replaced when the affected sections are no longer serviceable. Also, since the dimensions of the guide trough are selected to closely confine a particular product size, a change in the rolling schedule to a different product size will usually require replacing the entire guide trough with another trough properly dimensioned to handle the.
In accordance with the present invention, the known unitary guide trough is replaced by a plurality of channel-shaped guide sections carried on the periphery of a helical support plate. The guide sections are preferably identical, spaced one from the other, and removably secured to the support plate. With this arrangement, the support plate may be fabricated from one material selected for it strength and formability, e.g., ASTM A502, and the guide sections may be cast or machined from a different material selected for its resistance to frictional wear, e.g., ASTM 4140. Guide sections that undergo accelerated wear can be replaced while allowing the others to remain in place for continued extended use. A change in product size can be readily accommodated by simply changing only the guide sections without having to also replace the helical support plate.
These and other features and advantages of the present invention will now be described in greater detail with reference to the accompanying drawings, wherein: